Foraged native foods are the latest haute cuisine craze in Nordic countries like Finland and Denmark, where award-winning chefs are going into the woods to dig up an earthy new taste

February is the coldest month, and February in Denmark is about as bleak as it gets—until I reach Finland. Looking at the desolate fields near Lammefjorden outside Copenhagen, at first I don't see much to eat. But Soren Wiuff, a vegetable farmer, is digging up crosnes, tiny curlicue-shaped, artichoke-flavored roots, with his bare hands. A Danish TV crew is taking close-ups of my shoes punching through the frozen mud crust. It's hard to say which they find more entertaining: the idea that someone would visit a root-vegetable farm in Prada heels or that anyone would travel to the Nordic region in...